KR100458149B1 - Spiral wound gaskets, manufacturing method thereof and winding dies - Google Patents

Abstract

In order to provide a spiral wound gasket which allows easy centering of the gasket body and obtains excellent sealing property at low surface pressure, the spirally wound metal hoop material having a substantially V-shaped cross section and a filler are overlapped with each other. To prepare a spiral wound gasket. In the gasket of the present invention, the V-shaped bent portion of the hoop material is directed toward the inner periphery so that excellent centering can be obtained and the filler can be prevented from falling into the pipe.

Description

Spiral wound gaskets, manufacturing method thereof and winding dies

The present invention uses spiral wound gaskets for sealing fluids, such as water, oil, steam, gas, etc., which are used at joints of equipment or piping under high temperature and high pressure conditions. Hoop> and tape-shaped fillers (hereinafter referred to as fillers) made of asbestos, soft graphite, etc., overlapping each other and wound several times in the form of spiral winding], in particular parts used in automobile exhaust systems. A spiral wound gasket structure useful for use as a flange joint of an insert structure.

The spiral wound gasket is made of a prefabricated, tapered metal hoop having a cross section of approximately V shape, and filled with filler such as asbestos tape between each adjacent laminated surfaces thereof such that the V-shaped tip faces the outer periphery. It has a structure, which is called the basic form. In addition, gaskets of various types known as gaskets having an inner ring, gaskets having an outer ring, gaskets having an inner ring and an outer ring are known, and a gasket body by binding and centering thereof by pressure is known. In order to prevent deformation, one (or two) reinforcing metal ring (s) is mounted inside or outside the gasket body, or both inside and outside. Since the spiral wound gasket has a structure in which the filler having the metal hoop and the cushioning property is wound alternately, the elasticity is good and it can cope with thermal expansion and contraction. Therefore, the gasket is considered to be excellent in sealing property and ideal for high temperature. Therefore, the gasket is widely known as a gasket used for a part joint used in an exhaust system for automobiles, for example, an exhaust manifold, a front tube, and a silencer.

As a kind of filler, asbestos tapes, in which an asbestos sheet is cut in a band form, are generally used. However, asbestos fibers are natural minerals, which not only deplete resources, but also health problems that can be caused by asbestos fibers cause social problems and limit the use of asbestos worldwide. Tapes (hereinafter referred to as NA tapes) obtained by cutting the manufactured non-asbestos sheet are used.

For such NA tapes, various inorganic fibers (except asbestos) and needles in the form of needles or scales are blended and bound using a binder. Most of these, however, have a larger fiber diameter and a harder, less entanglement between different inorganic fibers in the fiber state compared to asbestos with a smaller fiber diameter. For this reason, when the spiral wound gasket using NA tape as the filler is directly exposed to hot gas and the binder in the NA tape is completely decomposed, the filler may easily fall off by vibration or the like.

In general, in the component joint of an automotive exhaust system, to improve the workability when two flanges are joined, an in-row portion 11 is formed as shown in FIG. 6. Here, the flange 9 of the upstream side exhaust pipe through which the exhaust gas 12 flows protrudes, the in-low portion 11 is inserted into the exhaust pipe, and the downstream side flange 10 is welded to the exhaust pipe. have. A spiral wound gasket 13 is inserted into the in-low portion 11 to seal the gap between the upstream side flange 9 and the downstream side flange 10. At this time, in order to improve the workability when the gasket main body 13 is mounted to the in-low part 11 or the flange is joined, the size of the gasket main body is larger than the outer diameter of the exhaust pipe of the in-low part 11. Adjust to be smaller than the inside diameter of the flange part. Thus, as shown in FIG. 6, the center of the gasket 13 can be moved from the center of the exhaust pipe and the gasket 13 can be mounted so that its filler material 14 can be directly exposed to the exhaust gas. Even in this case, no significant problem occurs when a conventional asbestos tape is used as the filler. However, in the NA tape, when the binder is pyrolyzed, since the bonding force between the inorganic material particles deteriorates, they are easily removed by vibration or the like. Therefore, there is a disadvantage that the sealing property deteriorates in a short time.

In order to solve this problem, the inner diameter of the gasket 13 is set to be approximately equal to the outer diameter of the exhaust pipe of the in-low portion 11, and the idle wound portion composed of the hoop only without the filler therein is increased. It is possible to prevent the filler 14 from being directly exposed to the exhaust gas. However, in addition to the fact that due to the increased hoop portion made of metal, the compression amount is smaller and the manufacturing cost is higher at low surface pressure, when the hoop material is inserted, two tip portions with approximately V-shaped hoops are inserted. Since this easily gets caught in the exhaust pipe, the inconvenience of difficult to arrange it is increased.

It is also conceivable to use a gasket having an inner ring in which the reinforcing metal ring is mounted inside the gasket body. However, since the weight of the entire gasket increases, this causes a problem that the manufacturing cost also increases because it counters the effort to reduce the weight and uses a punched or cut metal ring.

As another method known in the prior art, a ring-shaped structure for centering is integrally mounted inside a spiral wound gasket main body (Japanese Patent Application Laid-Open No. 3-93654). However, by this method, when the ring-shaped structure is mounted after the gasket body is formed, the number of steps is increased and the mounting work is complicated, while the ring-shaped structure is continuously manufactured while deforming the hoop shape for the body, Two types of rolls are required to bend the hoop, both of which increase manufacturing costs.

As another method, there is a spiral wound gasket in which a polygonal guide is mounted inside or outside the gasket body (see, for example, JP-A 4-7347O). In addition, by this method, an increase in manufacturing cost is inevitable because two kinds of rolls for bending the hoop and cutting both sides are required or an auxiliary core is required between the polygonal guide and the gasket body.

In addition to these centering characteristics, high rigidity flanges and coarse screws are not used in spiral wound gaskets used as automotive exhaust system components to reduce vehicle weight. It would be desirable to provide a spiral wound gasket with superior suitability for flange surfaces.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and its object is to provide a spiral wound gasket capable of easily centering the gasket body without increasing the manufacturing cost and having excellent sealing properties at low surface pressure.

In order to achieve the above object, the present invention is a spiral winding gasket wound spirally while the metal hoop material having a substantially V-shaped cross section and the filler overlap each other, the V-shaped bent portion of the hoop material is directed toward the inside The angle α of the bent portion is characterized in that 30 ° to 90 °. Here, the angle α is preferably 30 ° to 60 ° and the radius of curvature r of the leading bend is 0.4 to 1.3 mm.

Further, when winding the hoop material so that its approximately V-shaped tip faces inwardly, a rusting piece is used as a winding die with a groove having a groove having the same shape as the V shape along its periphery in the cross section. The die is manufactured so that it can be divided into two parts in the thickness direction to be disassembled. When manufacturing the hoop material in this manner, it is possible to overcome the problem of cost increase because the existing device can be manufactured with only a slight change without changing the productivity.

Although NA tape or soft graphite tape is suitable as a kind of filler, NA tape is preferable in terms of cost, and the type and shape of the hoop material are not limited.

In the spiral wound gasket according to the invention, in terms of construction, the basic form is most preferred for reducing weight. However, it can be a spiral wound gasket equipped with an outer ring without any inconvenience.

Description of the Preferred Aspects

The actual mode of the present invention may be configured, for example, as shown in Figs. In the figure, in the spiral wound gasket 1 formed by spirally winding the metal hoop material 2 and the filler material 3 with each other, the V-shaped bent portion 2a of the hoop material 2 has an inner periphery. The angle α of the tip bent portion 2a is 30 ° to 90 °, and the radius of curvature r of the tip bent portion 2a is 0.4 to 1.3 mm.

According to the invention, the approximately V-shaped tip bend 2a of the hoop material 2 of the gasket body is projected from the inner periphery and the tip of the innermost periphery is in contact with the in-low portion of the exhaust pipe circumscribed at the tip. Therefore, the gasket does not catch the hoop material when inserted, the gasket body does not protrude into the exhaust pipe, can be easily centered, and prevents the filler 3 from falling off because the filler 3 is not exposed to the exhaust gas. And the sealing property can be maintained for a long time.

In order to ensure that the filler material 3 does not come into contact with the exhaust gas, the inventors of the present invention have found that, in addition to the fact that the generally V-shaped tip bend 2a of the hoop material generally faces the inner periphery, an angle α is essentially necessary. It has been proven that it must be below 90 °. As the angle is reduced, the inventors increase the amount of crimping at low surface pressure, but if the angle is too small, the fact that the amount of crimping is too large and bends and the winding workability is poor, and to increase the crimping amount at low surface pressure. It has been found that the present invention can be achieved as the range of the angle α of the approximately V-shaped tip bend 2a of the most suitable hoop material 2 becomes clear.

In addition, the magnitude of the radius of curvature r is also important because the approximately V-shaped tip bend 2a of the hoop material 2 faces the inner periphery and the angle α is smaller than the angle of a conventional spiral wound gasket. If the radius is less than 0.4 mm, the filler 3 cannot be easily inserted into the tip bent portion 2a of the hoop material 2, and if the radius is too small, the hoop material 2 may be broken. On the other hand, when the radius of curvature r is large, the amount of compression at low surface pressure is large and excellent sealing characteristics are maintained. However, when the radius exceeds 1.3 m, it is confirmed that the amount of crimp is too large to bend and the sealing property deteriorates.

The invention will now be described in more detail using a number of aspects.

Different aspects of the spiral wound gasket according to the invention are constructed as shown in Figs. 1 to 3 and Fig. 4 shows an embodiment of their manufacturing method.

Aspect 1

In Embodiment 1, the approximately V-shaped tip bend 2a of the hoop material 2 in the basic gasket in which the inner diameter is 50 mm, the outer diameter is 63 mm, the thickness is 4.8 mm and the NA tape is used as the filler material 3 is used. Protrudes toward the inner periphery.

As a method of manufacturing the spiral wound gasket configured as described above, a tape-shaped thin plate made of SUS 304 used as the hoop material 2 is formed such that the angle α of the tip bending portion 2a is 45 ° and the radius of curvature r is 0.9 mm. It is made into a substantially V shape by a dishing method, and then placed in a winding die 6 having grooves 6a having the same cross-sectional shape as the hoop material 2 having a substantially V shape, as shown in Fig. 4A. . Using a pressurized part 8 having a shape opposite to the winding die 6, the pressure is applied to the hoop material and rotated once to wind the hoop material 2, and then the welding point is brought into close contact with the idle winding around the interior. (4) is formed. The filler 3 made of NA tape is then placed between two adjacent hoop material 2 layers and the two layers are wound so that they overlap each other. Subsequently, only the hoop material 2 is rotated once again without the filler and re-wound again and the welding point is brought into close contact to form the reel winding 5 around the outside to obtain a spiral wound gasket 1. Finally, the gasket 1 is separated by removing the upper part 7 of the winding die divided into two parts in the thickness direction.

Aspect 2

In Embodiment 2, the spiral wound gasket 1 is manufactured by a method substantially the same as the method of Embodiment 1. However, in Embodiment 1, the angle α of the tip bent portion 2a of the hoop material 2 is changed to 35 °, and the curvature radius r is changed to 1.2 nmn.

Aspect 3

In embodiment 3, the spiral wound gasket 1 is manufactured in substantially the same manner as in the method of embodiment 1. However, in Embodiment 1, the angle (alpha) of the tip bent part 2a of the hoop material 2 is changed to 60 degrees, and the curvature radius r is changed to 0.6 mm.

Comparative Example 1

In Comparative Example 1, the approximately V-shaped tip bent part 2a of the hoop 2 faces the outer periphery, and the diameter of the sealing part in contact with the flange is 60 °, and the radius of curvature r of the tip bent part 2a is 60 °. A conventional spiral wound gasket manufactured by the same method as that of Embodiment 1 except that the diameter of the hoop material 2 is 0.6 mm.

Comparative Example 2

Comparative Example 2 is a spiral wound gasket manufactured by the same method as in Embodiment 1 except that the angle α of the tip bent portion 2a of the hoop material facing the inner periphery is changed to 25 ° and the curvature radius r is changed to 1.4 mm.

Comparative Example 3

Comparative Example 3 is a spiral wound gasket manufactured by the same method as in Embodiment 1 except that the angle α of the tip bent portion 2a of the hoop material facing the inner periphery is changed to 100 ° and the radius of curvature r is changed to 0.3 mm.

Comparative Example 2 and Comparative Example 3 are not gaskets of the prior art, but are specially prepared in order to compare the characteristics of the gasket of the aspect of the present invention.

Table 1 shows the compression amount and the sealing property as a result of not only the structure of Embodiments 1-3 but also the structure and centering properties of Comparative Examples 1-3. Centering characteristics are determined by inserting the gasket into the in-low portion and measuring the operating size. In the crimping test, the target gasket is crimped by pressurizing the test apparatus and the amount of crimp is measured at a surface pressure of 200 kgf / cm ² . In the sealing test, a gasket is placed between two flanges holding the surface pressure at 200 kgf / cm ² and the pressure inside the flange is increased with air, and the amount of leaking air is measured at an internal pressure of 3 kgf / cm ² with a flow meter.

It can be seen from Table 1 that the spiral wound gasket according to the embodiment of the present invention has superior centering characteristics, a larger amount of compression, and a superior sealing characteristic than the gasket according to the comparative example.

In a spiral wound gasket constructed in accordance with the invention, for example, as shown in FIG. 5, it is inserted in the in-low portion 11 between the upstream side flange 9 and the downstream side flange 10 of the exhaust pipe. When using a gasket, an in-low portion 11 in which the approximately V-shaped bent portion 2a of the hoop material 2 protrudes from the gasket body toward the inner periphery and the innermost tip of the hoop material is bounded around the hoop material. ), The filler material 3 is not directly exposed to the exhaust gas, and the gasket body is not detached, thus maintaining excellent sealing properties for a long time.

As is clear from the above description, the use of the spiral wound gasket according to the present invention does not impair the suitability of the gasket due to the fact that the approximately V-shaped bend of the hoop protrudes from the gasket body toward the inner periphery. Since the expansion of the gasket body into the exhaust pipe can be prevented, the gasket body can be prevented from detaching and the initial sealing property can be maintained for a long time.

In particular, a large crimp amount and excellent sealing characteristics can be obtained by setting the radius of curvature r of the approximately V-shaped bent portion of the hoop material to 0.4 to 1.3 mm and the angle α of the bent portion to 30 to 90 degrees.

The spiral wound gasket of the present invention is easy to center the gasket body and can obtain excellent sealability at low surface pressure.

1 is a cross sectional view of an embodiment of the present invention,

2 is a plan view of an embodiment of the present invention,

3 is an enlarged cross-sectional view of a tip bent portion of the hoop material shown in FIG. 1,

4A and 4B are model diagrams illustrating the main parts of an apparatus for manufacturing a gasket according to an aspect of the present invention.

5 is a cross sectional view showing an example of a use state of an aspect of the present invention;

6 is a cross-sectional view showing an example of a state of use of the spiral wound gasket of the prior art.

Claims (3)

A spiral wound gasket in which a metal hoop material having a substantially V-shaped cross section and a filling material overlap each other and spirally wound, A spiral wound gasket, characterized in that the V-shaped bent portion of the hoop faces the inner periphery, the angle of the bent portion is 30 ° to 90 °, and the radius of curvature of the bent portion is 0.4 to 1.3 mm. A method of manufacturing a spiral wound gasket using a winding die for overlapping and winding a metal hoop material and a filler having a substantially V shape and a symmetrical thrusting piece for thrusting the winding member with the winding die. , The circumferential cross section is opened outward in a V shape, the opening angle is set to 30 ° to 60 °, the radius of curvature of the tip bend is set to 0.4 to 1.3 mm, and in the thickness direction to separate the spiral wound gasket after winding. A method of manufacturing a spiral wound gasket, characterized in that a winding die divided into two parts is used. A winding die used for producing a spiral wound gasket by winding a metal hoop material and a filler, which are approximately V-shaped, overlapping each other, And a circumferential die open in a V shape outwardly, set at an opening angle of 30 ° to 60 °, a radius of curvature of the tip bend set at 0.4 to 1.3 mm, and divided into two parts in the thickness direction.

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